Ernst Paul Specker (11 February 1920, Zürich – 10 December 2011, Zürich) was a Swiss mathematician. Much of his most influential work was on Quine's New Foundations, a set theory with a universal set, but he is most famous for the Kochen–Specker theorem in quantum mechanics, showing that certain types of hidden-variable theories are impossible. He also proved the ordinal partition relation ω² → (ω², 3)², thereby solving a problem of Erdős.

Specker received his Ph.D. in 1949 from ETH Zurich,^[1] where he remained throughout his professional career.